Method for concentrating the titanium oxide minerals in beach sand



United States Patent METHOD FOR CONCENTRATING THE TITA- NIUM OXIDE MINERALS IN BEACH SAND Robert E. Baarson, Westmont, 111., assignor to Armour and Company, Chicago, 111., a corporation of Illinois No Drawing. Application October 27, 1954, Serial No. 465,125

8 Claims. (Cl. 209-166) This invention relates to a method for concentrating the titanium oxide minerals in sand deposits which are usually known as beach sands. The invention also relates to a method for making a bulk separation of the heavy minerals in beach sands from the quartz.

Beach sands of the type with which the present invention is concerned may be found along the seashore, but are also found in large inland deposits in Florida and elsewhere. These sand beds or deposits are composed principally of quartz, while containing a small proportion of valuable minerals, and in particular titanium oxide mineral-s like ilmenite and rutile. Usually the content of quartz in these sands will be at least 90%, while the content of titanium oxide minerals ranges from 3% down to as little as .5 with .some sands falling outside of this range. For example, a typical Florida beach sand deposit may contain 94 to 96% quartz and from 1 to 2% of ilmenite and rutile. Small amounts of other titanium oxide minerals, such as leucoxene, may also be present, as well as a few percent of other heavy minerals. The most valuable product at present is the titanium oxide minerals, although other heavy minerals are of value, especially zircon and monazite.

At present titanium oxide minerals and other heavy minerals are being recovered from Florida beach sand deposits by a complicated and expensive procedure. The first step in the present process is to pass the beach sands through a series of spiral concentrators to make a rough separation of the titanium oxide and other heavy minerals from .the quartz. Following the rough separation, there are cleaner and recleaner spiral circuits to upgrade the rough concentrate, and a large amount of the middling material is recycled through these circuits to increase recovery. The equipment for carrying out these steps is bulky and expensive, and there is a serious problem of wear because of the abrasion of the concentrators by the sand. The titanium minerals in the heavy mineral concentrate are then further separated and concentrated by electrostatic and magnetic separators.

For the reasons indicated above, there has been a manifest need for a simpler process of separating titanium oxide minerals from the quartz in beach sand. Eflorts have been made to develop a flotation process which would produce this result, but heretofore such efforts have not met with success. This is somewhat surprising in view of the fact that the subdivided condition of beach sands is such as to make them a natural flotation feed. The mineral particles are completely liberated, and while the beach sands are composed of very fine particles, 90% of the particles are usually above 150 mesh. The problem, however, has been to provide a flotation method which would result in a sufnciently clean separation of the valuable mineral components in the beach sands from the quartz.

:It is therefore a general object of this invention to provide an improved method for concentrating the 'ice titanium oxide minerals in beach sands, and specifically, to provide a flotation method for accomplishing this result. More specifically, it is an object to provide a flotation method by means of which the titanium minerals in beach sands can be separated from the quartz. It is also an object of this invention to provide .a means for carrying out a bulk separation of the heavy mineralsin beach sand from the quartz therein. Further objects and advantages will appear as the specification proceeds.

This invention is based in part on the discovery that beach sands of the type found in inland deposits in Florida have films of organic material on the particles therein which interfere with the separation of the valuable minerals from the quartz by flotation. These organic films can be observed when the beach sand particles are examined under a microscope. The beach sands may also contain some separate organic matter, but this is quite distinct from the films, since the separate organic material can be removed from the beach sands by ordinary desliming procedures.

In practicing the present invention, the beach sand is first treated to remove the organic films from the sand particles. Preferably, this is accomplished by scrubbing the beach sand-s with a caustic like sodium hydroxide or potassium hydroxide. Specifically, an aqueous pulp or slurry of the beach sand can. be formed containing solids concentration of from 30 to and from /3 to 5 pounds of caustic added per ton of beach sand solids. This slurry or pulp is then mixed until the organic films have been removed from the particles, as can readily be determined by examining the particles under a microscope. Higher solids concentration up to at least 60 to 70% solids are preferred for caustic reagent economy, and if desired the treating step can be carried out in an attrition scrubber. p

The removed organic material is then preferably separated from the beach sand before continuing with the recovery operation. This can be done by the usual desliming procedures. For example, the caustic-treated pulp or slurry can be charged to a hydro-classifier or any type of apparatus designed for turbulent washing of mineral particles. This desliming operation will also remove any larger organic par-ticles which may have been present in the beach sand, in the event that the beach sand has not been subjected to a preliminary desliming operation before the caustic treatment. If desired the caustic scrubbing and desliming steps can be repeated.

Instead of sodium orpotassium hydroxide, other inorganic alkaline reagents can be used which are capable of producing a pH above 8. Preferably, a pH from 9 to 14 is employed, although the pH is not particularly critical. The important point is to have a suificient amount of the alkaline reagent present to completely liberate the organic films on the surfaces of the particles. Specifically, other alkali metal hydroxides can be used, as well as alkali metal carbonates and bicarbonates. The alkaline earth metal hydroxides, carbonates and bicarbonates can also be used with more or less success, and the mineral acids like sulfuric acid are of .some value.

The caustic-treated, deslimed beach sand is then formed into a flotation feed. Preferably, an aqueous slurry is formed containing from 15 to 30% beach sand solids, although this concentration can be varied. To the flotation feed is added an amine collector and a fluorinecontaining acid, and the pH of the aqueous feed is ad: justed to an acidic pH below 5.0. Sodium fluoride and sulfuric acid may also be added. Any beach sands which are substantially free of the organic films discussed above, can be formed directly into a flotation feed in this manner and if desired beach sand concentrates can be used. For example, the beach sands could first be processed by a gravity method to upgrade the titanium minerals to or more.

Any amine collector can be employed, and the specific amine collector is not critical. Preferably, however, the amine flotation agent is a primary amine containing a hydrophobic group of from 6 to 22 carbon atoms. Mixed amines like primary tallow and soya amines are suitable. Best results are achieved when the amine flotation agent is usedin the form of a water-soluble salt thereof, such as an amine acetate, hydrochloride or phosphate salt. Both mono-amines and poly-amines can be used.

The fluorine-containing acid is preferably hydrofluoric pass out in the overflow, although. these are of lesser importance than the titanium oxide minerals. However, it is significant that the method of this invention permits a clean separation to be made between all of the metal oxide and silicate minerals on the one hand and the quartz on the other.

This invention is further described in the following specific examples:

EXAMPLE I Prcparailon.-Scrub 500 grams of beach sand (as received) at 30% solids in hard water (Chicago tap water-pI-I7.9), with 4#/T NaOH. Deslime pulp twice and wash twice. One minute settling time allowed before each deslime or wash step. A Fagergren 500 gram cell acid, although other fluorine-containing acids can be subwas used for scrubbing and flotation. Temperature--- stituted, as well as mixtures of hydrofluoric acid and C.

Reagents and conditions Conditions Reagents #IT Point of Addition Time (Min.) Percent pH NaOH HF Armac MAAPO Cond. Float Solids 48% TD Scrub 5 30 After Deslime MAAPO-Frother composed of 50-50 mixture of methyl amyl alcohol and pine oil. Armac TDDistilled primary amine acetate derived from tallow fatty acids.

other fluorine-containing acids. The hydrofluoric acid or other fluorine-containing acid acts as a depressant for the Metallurgical results quartz Wt Wt Fai al- D'st The pH of the flotation slurry is critical, and should Product (mugs Pmht pergent g not exceed pH 5.0. Best results are achieved at pl-Is g ag r Percent ranging from 3.0 to 4.0. Part of the necessary hydro- 0 gen ion concentration to achieve the desired pH can be R1 20.2 4. 22 97.4 06.9 supplied by the fluorine-containing acid, but it will usually T 453 95 78 (L14 31 be preferred to use an additional acid, such as sulfuric Com osite 479.15 100.00 4. 23 100.0 or hydrochloric acid to maintain the flotation circuit at an 40 p 1 Specific gravity analysis made in tetrabrornoethaue-sp. gr. 2.95.

' EXAMPLE II Preparation.--Scrub 500 grams of beach sand (as received) at 30% solids in hard water (Chicago tap waterpH-7.9), with 4#/T NaOH. Deslime pulp twice and Wash twice. One minute settling time allowed before each deslirne or Wash step. A Fagergren 500 gram cell selves and may in some cases be used alone. Good rewas used for scrubbing and flotation. T cmperature- 'sults can be obtained with a -50 mixture of pine oil 50 30 C.

Reagents and conditions Conditions Reagents #/T Point of Addition Time (Min.) Percent pH NaOH HF H1304 Armac MAAPO 00nd. Float Solids 48% TD Scrub 5 30 4. 0 After Desllme 3 7. 8 R 1 2 20 & 0. 312 1.0 0. a5 0.1

MAAP O-Frother composed of 50-50 mixture of methyl amyl alcohol and pine oil. Armac TD-Distilled primary amine acetate derived from tallow fatty acids.

and isopropanol. The flotation operation itself can be M llurg cal results carried out in the usual type of flotation cells provided with means for supplying air to the lower portion of the Assay Wt. Wt. Percent- Districells. When the beach sand hasbeen treated and condi Product Granis remit Percent bufiony tioned as described and the flotation feed is at a pH below Heavy Percent 5.0, the titanium oxide minerals in the beach sand can Mmerals be readily floated away from the quartz. In other words, R 18 25 3 81 7 92 3 the titanium oxide minerals will be recovered in the over- Til:IIIIIIIIIIIIIIII 460:5 96:19 6:32 7:7 flow from the cells, while the quartz Wlll be depressed 47815 10 4.03 100.0 and will pass out 1n the underflow from the cells. The

other mineral constituents of the beach sand will also 1 Specific gravity analysis made in tetrabromoethane, sp. gr. 2.95.

EXAMPLE III Metallurgical results Preparation-Scrub 500 grams of beach sand (as re- Wt., Wt., Pir c e iii Districeived-untreated) at 30% solids in soft water (pH 6.3- Product Grams Percent 3233 local water obtained at site) with 4#/ T NaOH. Deslime 5 Mineral twice and Wash once. One minute settling time required 222 4 6 88.75 96. 5 before dcsliming or dewatering. A Fager-gren SOO-gram cell was used for scrubbing and flotation. Temperature 483-2 1000 100-0 1 Specific gravity analysis made in tetrabromoe hane-sp. gr. 2.95.

Reagents and conditions Conditions Reagents #IT Point of Addition Time (Min.) Percent pH NoOH HF HQSO Armac MAAPO Cond. Float Solids 48% TD MAAPO-Frother composed of 50-50 mixture methyl amyl alcohol and pine oil. Armac TDDistil1ed primary amine acetate derived from tallow fatty acids.

Metallurgical results Assay, Wt., Wt., Percent- Distri- Product Grams Percent Percent bution, Heavy Percent Mineral Composite 484. 95 100.0 4. 39 100.0

1 Specific gravity analysis made in tetrabromocthane-sp. gr. 2.95.

25 EXAMPLE v Conditions Reagents Point of Addition 'llme (Mln.) Percent pH NaOH HF IIZSOQ Annac MAAPO 00nd Float Solids 48% TD Scrub 2 30 Scrub. After Desl1mc.

MAAP O-Frother composed of -50 mixture of methyl amyl alcohol and pine oil. Armac TD-Distilled primary amine acetate derived from tallow fatty acids.

EXAMPLE IV Preparati0n.-Scrl1b 500 grams of beach sand (as received) for two minutes at 30% solids in demineralized water (pH-6.7).

Scrub for 5 minutes at 30% solids in deinineralized water with 1#/T NaOH. Deslimc pulp once and wash once.

One minute settling time was allowed for each deslime and washing step. A Fagergren SOD-gram cell was used for scrubbing and flotation. Temperature 30 C.

Reagents and conditions Deslime pulp once and wash once.

Metallurgical results 1 Specific gravity analysis made in tetrabromoethanesp. gr. 2.95.

Conditions Reagents #I'I Point of Addition Time (Min) Percent pH NnOH HF H2504 Armac MAAPO Cond. Float Solids 48% TD MAAPO--Frother composed of 50-50 mixture methyl amyl alcohol and pine oil. Armae TD-Distilled primary amine. acetate derived from tallow fatty acids.

7 EXAMPLE w M etallzifgical results Preparation-Beach sands (as received) scrubbed in Assay,

Wtx, Wt. Percent- Distriattritron scrubber at 76% solids for 3 minutes. Pulp Product Grams Perceht Percent bution, deslimed once and washed once. Scrub pulp at 30% 5 f g g Percent solids in soft Water for 2 minutes with %#/T NaOH. 1

Deslime pulp once and wash once. One minute settling R1" 7 14.37 9 85. 0 R1 32 6.39 31.38 12. 93 time allowed for each deshrne and wash step. A Fager- '11 397 79.24 0. as 1.87 gren SOO-gram flotation cell was used for 2nd scrub and W Composite 501 100.0 Edd flotation. Temperature 30 C.

Reagents and conditions Conditions Reagents Point of Addition Time (Min.) Percent pI-I NaOH HF HQSO Armac MAAPO Cond. Float Solids 48% T Attrition Scrub.

Scrub After Deslirne 5. In 1 2 20 5 i MAAPO-Frother composed of 50-50 mixture of methyl amyl alcohol and pine oil. Armac TTechnical primary amine acetate derived from tallow fatty acids.

Metallurgical results l Specific gravity analysis made in tctrabrdrnoethane-sp. gr. 2.95.

The method of this invention can also be advantageously used for the concentration of heavy minerals such as titanium oxide minerals from beach sand concentrates, as illustrated by the following example:

EXAMPLE VII Reagents and conditions Conditions Rea gents #/T Addition Percent Solids Time 00nd.

(Min.) Arman M A A T 0 Float 'l A l'ter (lcslimc. R

MAAPO-Frother composed of 50-50 mixture ol meth l ainyl alcohol and pine oil. A

Armac T-Prirnary amine acetate derived from tallcw kitty acids.

1 Composition of 15% EM Sand:

Specific gravity analysis onl for an additional test. Reagents and conditions similar to Example I.

Assay, Wt. W t., Percent- Distri- Product Grams Percent Percent bution, Heavy Percent Minerals Composite 495 100. 0 100. 0

While in the foregoing specification this invention has been described in relation to a specific embodiment thereof and many details have been set forth for this embodiment, it will be apparent to those skilled in the art that the invention is susceptible to other embodiments and that many of the details set forth herein can be varied widely without departing from the basic concepts of the invention.

I claim:

1. The method of concentrating titanium oxide minerals from beach sand having films of organic minerals on the particles therein and being composed principally of quartz particles while containing titanium oxide mineral particles, comprising removing the organic films from the particles of said sand, and then floating the titanium oxide mineral particles away from the quartz particles of. said sand in water containing an amine collector and a fluorine-containing acid and being at a pH below 5.0.

2. The method of concentrating titanium oxide minerals from beach sand having films of organic minerals on the particles therein and being composed principally of quartz particles while containing titanium oxide mineral particles, comprising treating said beach sand with an inorganic alkaline reagent to remove the organic films from the particles of said sand, and then floating the titanium oxide mineral particles away from the quartz particles of said sand in water containing an amine collector and a fluorine-containing acid and being at a pH below 5.0.

3. The method of claim 2 in which said alkaline reagent is an alkali metal hydroxide.

4. The method of concentrating titanium oxide minerals from beach sand having films of organic minerals on the particles therein and being composed principally of quartz particles while containing titanium oxide mineral particles, comprising scrubbing said beach sand with caustic to remove the organic films from the particles of said sand, separating the removed organic material from said sand, forming an aqueous flotation pulp of said sand containing an amine collector and a fluorinecontaining acid, and separating the titanium oxide mineral particles from the quartz particles by subjecting said flotation pulp to froth flotation at a pH below 5.0.

5. The method of concentrating titanium oxide minerals from beach sand having films of organic materials on the particles therein and being composed of at least 90% quartz particles while containing a substantial amount of ilmenite and rutile particles, comprising removing the organic films from the particles of said sand,

and then floating the ilmenite and rutile particles away from the quartz particles of said sand in Water containing an amine collector and a fluorine-containing acid and being at a pH below 5.0.

6. The method of concentrating metal oxide and silicate minerals from beach sand having films of organic material on the particles therein, said beach sand containing at least 90% quartz particles and less than 10% metal oxide and silicate mineral particles, comprising scrubbing said sand with caustic to remove the organic films from the particles thereof, separating the removed organic material from the sand, forming an aqueous flotation pulp of the sand containing an amine collector and a fluorine-containing acid depressant, subjecting said pulp to froth flotation at a pH below 5.0, and removing substantially all of said metal oxide and silicate minerals 10 in the overflow while removing substantially all of the quartz in the underflow.

7. In a method of concentrating heavy minerals from beach sands composed principally of quartz particles while containing heavy mineral particles, the step of floating the heavy mineral particles away from the quartz particles of said sand in water containing an amine collector and a fluorine-containing acid and being at a pH below 5.0.

8. In a method of concentrating heavy minerals from beach sand concentrates containing quartz particles and heavy mineral particles, the step of floating the heavy mineral particles away from the quartz particles of said sand concentrate in water containing an amine collector and a fluorine-containing acid and being at a pH below 5.0.

References Cited in the file of this patent UNITED STATES PATENTS Pickens Oct. 30, 1945 Moyer June 19, 1951 OTHER REFERENCES 

1. THE METHOD OF CONCENTRATING TITANIUM OXIDE MINERALS FROM BEACH SAND HAVING FILMS OF ORGANIC MINERALS ON THE PARTICLES THEREIN AND BEING COMPOSED PRINCIPALLY OF QUARTZ PARTICLES WHILE CONTAINING TITANIUM OXIDE MINERAL PARTICLES, COMPRISING REMOVING THE ORGANIC FILMS FROM THE PARTICLES OF SAID SAND, AND THEN FLOATING THE TITANIUM OXIDE MINERAL PARTICLES AWAY FROM THE ZUARTZ PARTICLES OF SAID SAND IN WATER CONTAINING AN AMINE COLLECTOR AND A FLOURINE-CONTAINING ACID AND BEING AT A PH BELOW 5.0. 